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sched/pelt: Use rq_clock_task() for hw_pressure

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commit 97450eb909 ("sched/pelt: Remove shift of thermal clock")
removed the decay_shift for hw_pressure. This commit uses the
sched_clock_task() in sched_tick() while it replaces the
sched_clock_task() with rq_clock_pelt() in __update_blocked_others().
This could bring inconsistence. One possible scenario I can think of
is in ___update_load_sum():

  u64 delta = now - sa->last_update_time

'now' could be calculated by rq_clock_pelt() from
__update_blocked_others(), and last_update_time was calculated by
rq_clock_task() previously from sched_tick(). Usually the former
chases after the latter, it cause a very large 'delta' and brings
unexpected behavior.

Fixes: 97450eb909 ("sched/pelt: Remove shift of thermal clock")
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Hongyan Xia <hongyan.xia2@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20240827112607.181206-1-yu.c.chen@intel.com
This commit is contained in:
Chen Yu 2024-08-27 19:26:07 +08:00 committed by Peter Zijlstra
parent 5d871a6399
commit 84d265281d
1 changed files with 2 additions and 1 deletions
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3
kernel/sched/fair.c
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@ -9719,9 +9719,10 @@ static bool __update_blocked_others(struct rq *rq, bool *done)
hw_pressure = arch_scale_hw_pressure(cpu_of(rq));
/* hw_pressure doesn't care about invariance */
decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
update_hw_load_avg(now, rq, hw_pressure) |
update_hw_load_avg(rq_clock_task(rq), rq, hw_pressure) |
update_irq_load_avg(rq, 0);
if (others_have_blocked(rq))